Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 14-04-2021, 07:21   #1
Registered User

Join Date: Dec 2018
Location: great white north
Boat: Beneteau F29
Posts: 2
Freshwater - calcareous buildup on propshaft

Any tips/tricks out there to mitigate buildup on running gear surfaces?


-Austenitic (non magnetic, but actual alloy unknown) SS prop shaft
-Mg shaft collar anode as well as Beneteau style propshaft nut Mg anode
-1.1 to -1.2v on an ag/agcl half cell in all possible combination of conditions (at and away from marina slip, AC power on and off, DC powered on and off, etc)
-located in Eastern Lake Ontario, freshwater
-boat sits at the slip for max 5-7 days at a time



After a season, I end up with a white calcareous buildup on the propshaft and prop. It's ugly but is removable with off the shelf descaling chemicals (CLR, or Zep, etc) but my main issue is the abrasive wear it causes to the cutless bushing, as it does form on the bearing surface of the propshaft


Everybody else that I see using (incorrect for freshwater) zinc anodes stuff looks clean as a whistle on haulout


Perhaps a switch to Al anodes?
mcswain29 is offline   Reply With Quote
Old 14-04-2021, 07:24   #2
Marine Service Provider
 
fstbttms's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 4,444
Re: Freshwater - calcareous buildup on propshaft

Quote:
Originally Posted by mcswain29 View Post
Perhaps a switch to Al anodes?
Umm... no.
Attached Thumbnails
Click image for larger version

Name:	zinc type chart.jpg
Views:	32
Size:	73.3 KB
ID:	236526  
fstbttms is offline   Reply With Quote
Old 14-04-2021, 07:28   #3
Marine Service Provider
 
fstbttms's Avatar

Cruisers Forum Supporter

Join Date: Oct 2006
Location: Under a boat, in a marina, in the San Francisco Bay
Posts: 4,444
Re: Freshwater - calcareous buildup on propshaft

My understanding (and I may be 100% incorrect about this) is that the calcareous buildup is actually the result of the actively depleting anode depositing ions onto the surrounding metals. That it is evidence of the anode doing its job.

How you mitigate it is beyond me however.
fstbttms is offline   Reply With Quote
Old 14-04-2021, 09:19   #4
Registered User

Join Date: Jun 2019
Location: Rochester, NY
Boat: Chris Craft Catalina 381
Posts: 2,026
Re: Freshwater - calcareous buildup on propshaft

I've been using aluminum anodes on Lake Ontario with good results for a couple of years now. The anodes do degrade, my props, shafts, etc. aren't showing signs of corrosion and when I measured, I was showing around -800mv (if I'm remembering correctly), which is enough to protect bronze and stainless (my only underwater metals). I should probably dig up my tools and re-measure at some point, as I'm not 100% sure of what my measurements were.

So I wonder if the magnesium anodes may just be a bit too much in your case, particularly considering the voltage you measured. Lake Ontario isn't the world's purest fresh water, so unless protecting aluminum or other more fragile metals, it's possible that magnesium anodes are overkill and aluminum will provide enough protection. Only way to know for sure is to try it, however.
rslifkin is online now   Reply With Quote
Old 15-04-2021, 10:59   #5
Registered User

Join Date: Dec 2014
Posts: 65
Re: Freshwater - calcareous buildup on propshaft

MG is the reason.
Too big anode or not enough exposed metal that has to be protected. Buy an aluminum anode.
Or just don't mind. As long as there are no hydrogen bubbles on that shaft surface
When atomic H is formed because of the electro chemical reaction. with mild steel it can get in to the metal and can cause hydrogen brittle ess.
I do not know about your shaft.
No bubbles, no problem.
jakkum is offline   Reply With Quote
Reply

Tags
cal, water

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
White Chalky Buildup on Prop and Shaft Natedogg Challenges 15 23-08-2017 16:15
Frost and Ice Buildup: The Enemy eating your Amps SV THIRD DAY Our Community 20 28-04-2016 11:59
Calcareous incrustation in the holding tank ricorrea2002 Plumbing Systems and Fixtures 1 22-10-2015 16:21
Greasy Black Battery Cap Buildup?? redsky49 Electrical: Batteries, Generators & Solar 0 27-04-2015 07:26
Scale Buildup in Toilet beau Plumbing Systems and Fixtures 20 04-04-2011 20:28

Advertise Here


All times are GMT -7. The time now is 09:36.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2021, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.